The present invention relates to a polynucleotide synthesizing apparatus used for synthesis of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) and the like.
A process for synthesizing DNA using a support to which a nucleoside is chemically bonded and successively condensing nucleotides by using the phosphite, triester phosphite and diester phosphite methods is well known. In this synthesis process, the steps of washing, deprotection, washing, condensation reaction, and washing and the like are repeated. Accordingly, the number of repetitions is high and the operation is troublesome in spite of the small number of steps.
Recently, various automatic DNA synthesizing apparatuses have been proposed for the purpose of eliminating the complexity of the synthesis operation.
The automatic DNA synthesizing apparatuses which have heretofore been proposed are adapted to be controlled by means of a microcomputer having a 128 to 512 k bit system memory and a 128 to 512 k bit user memory. However no sequence controller has been used to control the proposed polynucleotide synthesizing apparatus, since it has been found impossible for prior art sequence controllers to carry out control of the automatic DNA synthesizing apparatus, and this has been accomplished by a compact and economical programmable controller. While the programmable controller makes sophisticated control possible, the synthesizing apparatus is more bulky and more expensive than a synthesizing apparatus using microcomputer. Therefore no efforts have been made for practical use.
Since removal of a housing for incorporation of the controller using the afore-mentioned versatile microcomputer into the synthesizing apparatus will influence the reliability etc., the controller should be mounted on the housing of the synthesizing apparatus. This makes the housing of the entire apparatus more bulky. In addition, an interface for connection of the microcomputor with the synthesizing apparatus, relay devices for controlling the liquid charge and discharge means, a noise elimination device, and power regulator etc are required. Furthermore special specification of these interfaces causes high cost.
Although a controller using a dedicated P.C. board enables the entire apparatus to be compact, the board itself should be specially designed and the afore-mentioned interface is required, thereby involving high cost. Research and development cost is required whenever the P.C. board itself should be converted for modifying the program.
In other words, utilization of the microcomputer as a controller in view of the convenience of the microcomputer not only makes the synthesizing apparatus more bulky and expensive, but also sophisticated operation peculiar to the computer is required.